Benzodioxinothiophenes, their preparation and use

ABSTRACT

The invention relates to substituted or unsubstituted benzodioxinothiophenes, their preparation and their use for preparing electrically conductive oligomers or polymers, also oligomers or polymers comprising these thiophene derivatives as repeating unit.

BACKGROUND

[0001] The invention relates to substituted or unsubstitutedbenzo-dioxinothiophenes, hereinafter referred to as3,4-(1′,2′-benzo-dioxy)thiophene, a process for preparing it and its usefor preparing electrically conductive oligomers or polymers. Theinvention further relates to oligomers or polymers which comprise thesecompounds as repeating unit.

[0002] Conductive organic polymers have a wide range of applications. Anexample which may be mentioned is their use for producing polymerbatteries, diodes or transistors or solar cells. As conductive organicpolymers, use is made of, for example, systems based on polyacetylene,poly(p-phenylene), polythiophene or polypyrrole.

[0003] There are some electrically conductive oligomers and polymerswhich can be prepared from thiophene derivatives. Previously knownelectrically conductive oligomers and polymers prepared from thiophenederivatives have aliphatic substituents. A particular example isprovided by polymers based on 2,3-dihydrothieno[3,4-b][1,4]dioxin, whichis also referred to as 3,4-ethylenedioxythiophene in the literature andis commercially available under the name BAYTRON® M from BAYER AG.

[0004] To be able to match the polymer properties to the respectiverequirements in a targeted way, it is necessary to have many suitablemonomer building blocks available. It is therefore an object of thepresent invention to provide new thiophene derivatives and to find waysof preparing them.

SUMMARY

[0005] The invention relates to a compound of the Formula (I):

[0006] in which R¹ and R² are each, independently of one another, H,C₁-C₂₀-alkyl, C₆-C₁₀-aryl, C₇-C₁₂-aralkyl, C₁-C₁₈-alkoxy,C₂-C₁₈-hydroxyal-kylenoxy, C₂-C₃₆-alkoxyalkylenoxy, hydroxyethyl,formyl, C₂-C₁₈-acyl, nitro, halogen, sulfo (—SO₃H), cyano (—CN), carboxy(—COOH), C₁-C₁₈-alkoxy-carbonyl or trifluoromethyl, or together with thearomatic ring to which they are bound form a fused aromatic ring system,and X is N or C—H.

[0007] The invention also relates to a process for preparing a compoundof the Formula (I) that involves reacting a 3,4-dialkoxythiophene with asubstituted or unsubstituted 1,2-dihydroxybenzene, and thereby makingthe compound of Formula (I).

[0008] The invention also relates to a process for making anelectrically conductive polymer comprising polymerizing a compound ofthe Formula (I).

[0009] And the invention relates to an electrically conductive polymercomprising at least one repeating compound of the Formula (I).

[0010] The invention is further described in the following illustrativeexamples in which all parts and percentages are by weight unlessotherwise indicated.

DESCRIPTION

[0011] New thiophene derivatives have now been able to be prepared.These are substituted or unsubstituted 3,4-(1′,2′-benzodioxy)thiophene,which term includes compounds containing a diazabenzo radical. Thecompounds can bear a wide variety of different substituents whichinfluence the electronic structure in a targeted manner, so that theyare particularly interesting and versatile as monomers for preparingconductive polymers.

[0012] The invention provides compounds of the Formula (I):

[0013] in which R¹ and R² are each, independently of one another, H,C₁-C₂₀-alkyl, C₆-C₁₀-aryl, C₇-C₁₂-aralkyl, C₁-C₁₈-alkoxy,C₂-C₁₈-hydroxyalkylenoxy, C₂-C₃₆-alkoxyalkylenoxy, hydroxyethyl, formyl,C₂-C₁₈-acyl, nitro, halogen, sulfo (—SO₃H), cyano (—CN), carboxy(—COOH), C₁-C₁₈-alkoxycarbonyl or trifluoromethyl, or together with thearomatic ring to which they are bound form a fused aromatic ring system,and

[0014] X is N or C—H.

[0015] Preference is given to R¹ and R² each being, independently of oneanother, H, C₁-C₁₆-alkyl, C₆-C₁₀-aryl, C₁-C₁₈-alkoxy, C₂-C₄-acyl, nitro,halogen, e.g., fluorine, chlorine or bromine, orC₂-C₃₆-alkoxy-alkylenoxy, particularly preferably H, methyl, butyl,phenyl, acetyl (—CO—CH₃), methoxy, methoxyethoxy (H₃C—O—CH₂—CH₂—O—),nitro or chlorine. Very particular preference is given to at least oneof the radicals R¹ and R² being hydrogen.

[0016] X is preferably C—H.

[0017] The compounds of the Formula (I) represent a valuable supplementto the known thiophene derivatives having aliphatic substituents sincethey are suitable for preparing conductive polymers having particularlyfavorable properties, in particular a high conductivity. Such polymerscan be used, for example, as electrodes.

[0018] Compounds of the Formula (I) in which X is C—H can be preparedby, for example, reacting 3,4-dialkoxythiophene, preferably the known3,4-dimethoxythiophene, with substituted or unsubstituted1,2-dihydroxy-benzenes.

[0019] This reaction can take place, for example, at atmosphericpressure in an aromatic solvent such as xylene or toluene at from about100 to about 160° C., preferably reflux temperature, in the presence ofan acid catalyst, e.g., sulfuric acid or p-toluenesulfonic acid.

[0020] Compounds of the Formula (I) in which X is N can be prepared by,for example, reacting a known 3,4-dihydroxythiophenedicarboxylic esterwith a substituted or unsubstituted 2,3-dihalo-1,4-diazabenzene andsubsequently saponifying and decarboxylating the product of thisreaction.

[0021] The compounds of the Formula (I) can be used for preparingelectrically conductive polymers. Here, it is possible to use either onecompound of the Formula (I) as monomer or a mixture of various compoundswhich come under the definition of Formula (I). It is also possible toadd further thiophene derivatives, in particular the known3,4-ethylenedioxy-thiophene, as monomers in addition to one or morecompounds of the Formula (I).

[0022] The polymerization is carried out in accordance withpolymerization procedures for known thiophene derivatives. It can becarried out, for example, oxidatively using oxidants such as iron(III)chloride or other -iron(III) salts, H₂O₂, sodium or potassiumperoxodisulfate, potassium dichromate, potassium permanganate orelectrochemically.

[0023] The invention further provides for the use of compounds of theFormula (I) for preparing electrically conductive polymers and provideselectrically conductive polymers which are prepared by polymerization ofa compound of the Formula (I) and therefore comprise at least onecompound of the Formula (I) as repeating units.

[0024] The invention is further described in the following illustrativeexamples in which all parts and percentages are by weight unlessotherwise indicated.

EXAMPLES Example 1

[0025] 45 g of 3,4-dimethoxythiophene (0.31 mol), 33 g of catechol (0.3mol), 60 ml of xylene, 1.5 g of p-toluenesulfonic acid and 0.6 g oftriphenylphosphine were heated to boiling (145° C.) under protective gasfor 24 hours. Methanol formed was distilled off during this time.

[0026] To monitor the course of the reaction, samples were taken atintervals and analyzed by HPLC. The reaction was stopped as soon as allof the 3,4-dimethoxythiophene used had reacted.

[0027] After cooling, the mixture was extracted four times with 50 mleach time of cyclohexane. The first cyclohexane extract was deep reddishbrown, and the following extracts became increasingly light in color andcontained increasingly pure product. The extracts were combined andallowed to stand overnight, resulting in precipitation of a dark reddishbrown oil which was separated off.

[0028] The oil was evaporated on a rotary evaporator and freed of xyleneand taken up in 200 ml of cyclohexane.

[0029] The combined cyclohexane solutions were admixed with 0.4 g ofactivated carbon, heated to 70° C. and filtered. The clarified solutionwas evaporated to dryness on a rotary evaporator (70° C., 25 mbar).

[0030] This gave 14.8 g of slightly yellowish product which had amelting point of 60° C. and, according to GC-MS analysis, contained 99%of benzothienodioxin (3,4-(1′,2′-benzodioxy)thiophene). MS: m/e=190(100%).

[0031] The product was purified further by chromatography (eluant:cyclohexane, on silica gel as stationary phase). This gave a pure white,crystalline product which melts at 72° C.

[0032] In the infrared spectrum (KBr pellet), the product absorbsstrongly at 1509, 1493,1281, 766 and 742 cm⁻¹.

[0033] 1H—NMR (CDCl₃): 6.39 ppm (s, 2H), 6.88 ppm (s, 4H).

[0034] The compound can be polymerized, for example electrochemically,to form an electrically conductive film or firstly polymerized byoxidation using iron(III) tosylate in ethanol and then processed fromchloroform to give an electrically conductive film.

EXAMPLE 2

[0035] 12.5 g of 3,4-di-n-propyloxythiophene, 20.7 g of4-tert-butylcatechol and 1.2 g of p-toluenesulfonic acid monohydratewere refluxed in 90 ml of toluene under a protective gas atmosphere for3 hours. A mixture of toluene and n-propanol which had been formed wassubsequently distilled off. The amount of solvent distilled off wasreplaced in portions firstly by toluene, then by xylene. Distillationwas continued for a total of 12 hours. The course of the reaction wasmonitored by means of thin-layer chromatography.

[0036] After the reaction was complete, the mixture was cooled and thedark solution obtained was washed three times with water. The solventwas distilled off under reduced pressure on a rotary evaporator and theblack residue was purified by preparative column chromatography (on SiO₂(silica gel) as stationary phase using toluene as eluant). This gave16.6 g of a dark red oil which, according to 1H-NMR, contained 65% of3,4-(4′-tert-butylbenzo-1′,2′-dioxy)thiophene.

[0037] 1H—NMR (CDCl₃): 1.28 ppm (9H, s), 6.40 ppm (2H, s), 6.8-6.95 ppm(2H, aromat. AB system), 6.94 ppm (1H, s).

Example 3

[0038] Polymerization of 3,4-(1′,2′-benzodioxy)thiophene 5.0 g ofiron(III) p-toluenesulfonate were dissolved in 10.4 g of ethanol. 0.58 gof 3,4-(1′,2′-benzodioxy)thiophene were added to the solution. Themixture was stirred at room temperature for 1 hour and the solution wassubsequently poured onto a glass plate or another substrate and thelayer was spread to form a thin film, for example by spin coating. Thefilm was subsequently dried at 75° C. for 1 hour.

[0039] This gave a dark blue film having a slight violet tinge. The filmwas somewhat darker than a comparative film which had been obtained from3,4-ethylenedioxythiophene under identical conditions.

[0040] The film displayed electrical conductivity.

[0041] Although the invention has been described in detail in theforegoing for the purpose of illustration, it is to be understood thatsuch detail is solely for that purpose and that variations can be madetherein by those skilled in the art without departing from the spiritand scope of the invention except as it may be limited by the claims.

What is claimed is:
 1. A compound of the Formula (I):

wherein R¹ and R² are each, independently of one another, H,C₁-C₂₀-alkyl, C₆-C₁₀-aryl, C₇-C₁₂-aralkyl, C₁-C₁₈-alkoxy,C₂-C₁₈-hydroxy-alkylenoxy, C₂-C₃₆-alkoxyalkylenoxy, hydroxyethyl,formyl, C₂-C₁₈-acyl, nitro, halogen, sulfo (—SO₃H), cyano (—CN), carboxy(—COOH), C₁-C₁₈-alkoxycarbonyl or trifluoromethyl, or together with thearomatic ring to which they are bound form a fused aromatic ring system,and x is N or C—H.
 2. The compound according to claim 1, wherein R¹ andR² are each, independently of one another, H, C₁-C₁₆-alkyl, C₆-C₁₀-aryl,C₁-C₁₈-alkoxy, C₂-C₄-acyl, nitro, halogen or C₂-C₃₆-alkoxyalkylenoxy. 3.The compound according to claim 2, wherein R¹ and R² are each,independently of one another, H, methyl, butyl, phenyl, acetyl(—CO—CH₃), methoxy, methoxyethoxy, nitro or chlorine.
 4. The compoundaccording to claim 1, wherein at least one of the radicals R¹ and R² isH.
 5. The compound according to claim 1, wherein X is C—H.
 6. A processfor preparing a compound of the formula (I):

wherein R¹ and R² are each, independently of one another, H,C₁-C₂₀-alkyl, C₆-C₁₀-aryl, C₇-C₁₂-aralkyl, C₁-C₁₈-alkoxy,C₂-C₁₈-hydroxy-alkylenoxy, C₂-C₃₆-alkoxyalkylenoxy, hydroxyethyl,formyl, C₂-C₁₈-acyl, nitro, halogen, sulfo (—SO₃H), cyano (—CN), carboxy(—COOH), C₁-C₁₈-alkoxycarbonyl or trifluoromethyl, or together with thearomatic ring to which they are bound form a fused aromatic ring system,and x is N or C—H, the process comprising reacting a3,4-dialkoxythiophene with a substituted or unsubstituted1,2-dihydroxybenzene, and thereby making the compound of Formula (I). 7.The process of claim 6, wherein R¹ and R² are each, independently of oneanother, H, C₁-C₁₆-alkyl, C₆-C₁₀-aryl, C₁-C₁₈-alkoxy, C₂-C₄-acyl, nitro,halogen or C₂-C₃₆-alkoxyalkylenoxy.
 8. The process according to claim 6,wherein R¹ and R² are each, independently of one another, H, methyl,butyl, phenyl, acetyl (—CO—CH₃), methoxy, methoxyethoxy, nitro orchlorine.
 9. The process according to claim 6, wherein at least one ofthe radicals R¹ and R² is H.
 10. The process according to claim 6,wherein X is C—H.
 11. A process for making an electrically conductivepolymer comprising polymerizing a compound of the Formula (I):

wherein R¹ and R² are each, independently of one another, H,C₁-C₂₀-alkyl, C₆-C₁₀-aryl, C₇-C₁₂-aralkyl, C₁-C₁₈-alkoxy,C₂-C₁₈-hydroxyalkylenoxy, C₂-C₃₆-alkoxyalkylenoxy, hydroxyethyl, formyl,C₂-C₁₈-acyl, nitro, halogen, sulfo (—SO₃H), cyano (—CN), carboxy(—COOH), C₁-C₁₈-alkoxycarbonyl or trifluoromethyl, or together with thearomatic ring to which they are bound form a fused aromatic ring system,and X is N or C—H, and thereby forming the electronically conductivepolymer.
 12. The process according to claim 11, wherein R¹ and R² areeach, independently of one another, H, C₁-C₁₆-alkyl, C₆-C₁₀-aryl,C₁-C₁₈-alkoxy, C₂-C₄-acyl, nitro, halogen or C₂-C₃₆-alkoxyalkylenoxy.13. The process according to claim 11, wherein R¹ and R² are each,independently of one another, H, methyl, butyl, phenyl, acetyl(—CO—CH₃), methoxy, methoxyethoxy, nitro or chlorine.
 14. The processaccording to claim 11, wherein at least one of the radicals R¹ and R² isH.
 15. The process according to claim 11, wherein X is C—H.
 16. Anelectrically conductive polymer comprising at least one repeatingcompound of the Formula (I):

wherein R¹ and R² are each, independently of one another, H,C₁-C₂₀-alkyl, C₆-C₁₀-aryl, C₇-C₁₂-aralkyl, C₁-C₁₈-alkoxy,C₂-C₁8-hydroxyalkylenoxy, C₂-C₃₆-alkoxyalkylenoxy, hydroxyethyl, formyl,C₂-C₁₈-acyl, nitro, halogen, sulfo (—SO₃H), cyano (—CN), carboxy(—COOH), C₁-C₁₈-alkoxycarbonyl or trifluoromethyl, or together with thearomatic ring to which they are bound form a fused aromatic ring system,and x is N or C—H.
 17. The polymer according to claim 16, wherein R¹ andR² are each, independently of one another, H, C₁-C₁₆-alkyl, C₆-C₁₀-aryl,C₁-C₁₈-alkoxy, C₂-C₄-acyl, nitro, halogen or C₂-C₃₆-alkoxyalkylenoxy.18. The polymer according to claim 16, wherein R¹ and R² are each,independently of one another, H, methyl, butyl, phenyl, acetyl(—CO—CH₃), methoxy, methoxyethoxy, nitro or chlorine.
 19. The polymeraccording to claim 16, wherein at least one of the radicals R¹ and R² isH.
 20. The polymer according to claim 16, wherein X is C—H.